The present invention is directed to a technique for transmitting a radio message signal on a subcarrier of a main frequency while a radio program is being broadcast and, more particularly, to the display of such a message simultaneously with continuous audible reproduction of the radio program.
Various techniques have been proposed for utilizing the airwaves to communicate not only a radio program to its listeners, but also to convey other programs and information as well. For example, continuous background music, paging signals, and stock market information are carried on subcarrier frequencies. However, those previous approaches have not displayed a "live", i.e. dynamic, message while the audio reproduction of the program continues uninterrupted. Such a "live" message would preferably be of any desired length, but would have to be displayed by multiple number of segments, with the maximum segment length being determined by the size of the display. Previous approaches have used a static display. For example, the Dec. 1988 issue of Radio-Electronics includes on pages 65-68 and 76 an article on a European data system used in conjunction with FM programming. A subcarrier, typically at 57 kHz, is used to carry digital data for display on a radio. The displayed information describes the audio program as being "sports" or "traffic", or it is the name/number of the radio station. As such, the displayed message is static.
It would be highly desirable to continue uninterrupted playing of the radio program while the transmitted message is being dynamically reproduced for viewing by the radio station listener. The radio programming, such as music, can continue uninterrupted while, for example, the traffic conditions are being displayed rather than having to be audibly reproduced. With the system presently in use, traffic announcements, commercials, announcements, news and such cut into the enjoyment of a musical radio program and detract from the continuity of a discussion program, for example. Some radio stations may be reluctant to carry such audible messages knowing full well that the programming for which its sponsors are paying will be interrupted by it. It would be highly advantageous to have a system which can reproduce the message signal for the benefit of the listener but without cutting into the normal program being broadcast by the radio station. Were such a system available, all the parties involved would benefit. Specifically, sponsors of the radio program could feel assured that the program and/or the advertisements for which they are paying would not be interrupted by an emergency announcement, for example. The radio station may find it easier to attract sponsors and, in addition, may succeed in keeping a broader range of listeners including those who are not interested in tuning to an audio program likely to be interrupted. There is also an economic incentive in perhaps receiving revenue for both the regular programming and the message transmission which are occurring at the same time whereas, otherwise, a given interval of time would be devoted to only one of the two. In addition, the listener would be pleased because the enjoyment of the program is maximized due to the lack of interruptions while, at the same time, gaining the flexibility of obtaining a reproduced message signal which is of assistance in, for example, traffic conditions or any of the other types of uses to which such a message signal can be put.